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Women can see more colors then menJune 19, 2012

An average person can perceive a million different colors.Our power of color vision derives from cells in our eyes called cones. There three types of cones each triggered by different wave lengths of light. Every moment our eyes are open, those three flavors of cones fire off messages to the brain. The brain then combines the signals to produce the sensation of light and color.

Vision is complex, but the calculus of color is strangely simple. Each cone confers the ability to distinguish the ability to distinguish around a hundred of shades, so the total number of combinations is at least 100e3, or a million. Take one type of cones away (go from what scientists call a trichromate to a dichromate) and the number of possible combinations drops a factor of 100, to 10000. Almost all other mammals, including dogs and monkeys, are dichromates. The richness of the world we see is rivaled only by that of birds and some insects, which also perceive the UV spectrum.

Researchers suspect,though, that some people see even more. Living among us are people with four types of cones, who might experience a range of colors invisible to the rest of us. It's possible these tetrachromates see a hundred million colors, with each familiar hue fractioning into hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way to of knowing they see far beyond what we consider the limits of human vision.

Over the course of two decades, Newcastle University neuroscientist Gabrielle Jordan and her colleagues have been searching for people endowed with this supervision. Two years ago, Jordan finally found one. A doctor living in Northern England, referred to as only cDa29 in the literature, is the first tetrachromat known to science. She is almost surely not the last one...

A recent paper by Kimberly Jameson, Susan Highnote and Linda Wasserman of the University of California, San Diego, showed that up to 50 % of women carry 4 types of iodopsins and can employ their extra pigments in "contextually rich viewing circumstances".

For example, when looking at a rainbow, these females can segment it into about 10 different colors, while trichromat (with three iodopsins) people can see just seven: red, orange, yellow, green, blue, indigo and violet. For tetrachromat women, green was found to be assigned in emerald, jade, verdant, olive, lime, bottle and 34 other shades.